| Literature DB >> 8411176 |
A F Monzingo1, E J Collins, S R Ernst, J D Irvin, J D Robertus.
Abstract
The pokeweed antiviral protein (PAP), isolated from the leaves of Phytolacca americana, is one of a family of plant and bacterial ribosome-inhibiting proteins (RIPs) which act as specific N-glycosidases on rRNA. Here we report the three-dimensional structure of PAP determined to 2.5 A resolution by X-ray crystallography. After 14 rounds of refinement, the R factor is 0.17 for 5.0 to 2.5 A data. The protein is homologous with the A chain of ricin and exhibits a very similar folding pattern. The positions of key active site residues are also similar. We also report the 2.8 A structure of PAP complexed with a substrate analog, formycin 5'-monophosphate. As seen previously in ricin, the formycin ring is stacked between invariant tyrosines 72 and 123. Arg179 bonds to N-3 which is thought to be important in catalysis.Entities:
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Year: 1993 PMID： 8411176 DOI： 10.1006/jmbi.1993.1547
Source DB: PubMed Journal: J Mol Biol ISSN： 0022-2836 Impact factor: 5.469